用简便方法计算：21.5^2-3*21.5+1.5^2-100

Question

如题所述

Answer 1

21.5^2-3*21.5+1.5^2-100
=21.5*21.5-3*21.5+1.5^2-100
=(21.5-3)*21.5+1.5^2-100
=18.5*(20+1.5)+1.5^2-100
=18.5*20+(18.5*1.5+1.5*1.5)-100
=18.5*20+20*1.5-100
=20*20-100
=400-100=300